Venetian blind ladder



March 11, 1952 T. A. MARTIN ETAL 2,588,550

VENETIAN BLIND LADDER Filed Jan. 5, 1949 INVENTORS 5/0/1445 ,4. M4277 BY doszp/llf/u/vrm Wei W Patented Mar. 11, 1952 UNITED STATES PATENT OFFICE 2,588,550 I VENETIAN BLIND LADDER Thomas A. Martin and Joseph L. Hunter, Riverside, Calif., assignors to Hunter Douglas Cor poration, Riverside, Galif., a corporation of Delaware Application January 3, 1949, Serial No. 68,866 2' Claims. (01. 160 178) This invention relates to Venetian blinds and has particular reference to a construction of the ladderswhich are employed on Venetian blinds for the purpose of supporting the Venetian blind slats in spaced relation to each other in the normal functioning of the blind.

While our invention is particularly adapted for use with the type of slat known as removable slat, that is, a slat which is formed with cord openings such as to permit the ready disengagement of the slats from the cords and to per mit the removal of the slats for cleaning purposes without requiring the complete disassembly of the blind, however, it should be understood that the construction illustrated,' described and claimed herein, is likewise adaptable for use with the standard type of Venetian blind slat, namely one in which the cord opening extending through the slats are formed as elongated slots extending transversely of the slats but not extending to the edge thereof, as distinguished from the removable slats in which the cord openings Will-com prise elongated slots one end of which will extend to the edge of the slats to facilitate the removal of the slats from the cords and from the blind when it is desired to do so.

As will be readily understood by those skilled in this art, the ladders employed for Venetian blinds utilize vertical webs or tapes which must be extremely flexible so as to permit the ready flexing or bunching of the vertical tapes as the Venetian blind is raised. The usual construction of Venetian blind ladders is that the vertical tapes are interconnected at substantially evenly spaced intervals with cross bars, upon which the slats assembled upon the blind may rest, so that the slats are supported in anadequate fashion. The vertical tapes of the ladder are arranged to be raised and lowered relative to each other in order to tilt the slats relative to each other as the Venetian blind is to be moved from open to closed position. 7

While at the present time the conventiona Venetian blind is constructed with ladders which are made from woven or otherwise fabricated fabric material, in which the cross bars are formed of similar materialfthat is, material which is as flexible as the vertical tapes employed in the ladders. It is therefore, the broad purpose of our invention to provide a Venetian blind ladder in which the cross bars are formed ofa material which is stifier or more rigid than the material of the vertical tapes.

We have disclosed in our co-pending application, Serial No. 12,447, filed March 1, 1 948,-now

U. S. Patent 2,535,926, for Venetian blind a construction of Venetian blind ladders which this feature of utilizing cross bars or more stiff or more rigid material than flexible vertical tapes is incorporated. In that application, however, it is contemplated that the material which is to be used for the cross bars will be a stiff material which is stiff of its own construction, whereas in the present invention it is an object to provide a ready means for providing a stiilening member which'may'be employed as an adjunct with a substantially flexible material such as the same material of which the flexible vertical tapes are made. In a co-pe'nding application Serial No. 730,777, filed'February 25, 1947, now abandoned, for a Venetian blind ladder construction, filed by one of us, there is disclosed and claimed a Venetian blind ladder construction in which reinforcing fillets are disposed at the juncture of the cross bars with the vertical tapes to strengthen the articulated connection between them and prevent possible tearing of the cross bars from the vertical tapes.

Another object of our invention is to provide a Venetian blind ladder utilizing the feature of cross bars which are stiifened by the employment of a stiffening member, which i especially adapted for use with ladders formed of plastic material such as the ladders disclosed in our United States Letters Patent issued to Joseph L. Hunter No. 2,405,579, 011 August 13, 1946. Since it is the feature of our invention to provide a stiffening member which is formed of suitable material about which may be formed a plastic coating corresponding to the plastic material of which the balance of the ladder is made.

Another object of our invention is to provide a Venetian blind ladder of the character set forth wherein the sti-ifening member comprises a strip of material having the desired rigidity which may be employed as a core about which may be extruded or otherwiseapplied a coatingor covering of plastic material corresponding to the plastic material of which the remainder of the ladder is made.

Another object of our invention is to provide a ladder'of the character'described in which the core material may be relatively thin sheet metal, over which i placed the plastic covering so that the external appearance of the cross bars is the same as that of the remainder of the ladder.

Another object of our invention is to provide a stiffening member for the cross bars of the Venetian blind ladders wherein the stiffening material extends substantially the full length of the,

cross bars, that is, substantially the full length of that portion of the cross bars disposed between the two vertical tapes to which they are attached, the stiffening material, however, stopping short of actual contact with the vertical tapes to thereby provide a hort section of relatively flexible material, such as flexible plastic, to form a flexible hinge between the cross bars and vertical tapes.

Another object of our invention is to provide a construction of the character described, wherein the cross bar material may be made up in strips of relatively great length including the stinening core material, with flexible edge sections, which strips may be subsequently cut into suitable lengths to form the cross bars and then be joined to the vertical tapes to form the finished ladder.

Another object of our invention is to provide a construction of the character set forth in the preceding paragraphs, wherein the extreme edge of the strip or the extreme ends of the cross bar sections flare outwardly so as to provide fillets at the point of junction between the cross bars and the vertical tapes, to thereby strengthen the joint between the cross bars and the vertical tapes and avoid or minimize the separation of the cross bars from the vertical tapes.

Other objects of our invention will be apparent from the study of the following specification, made in connection with the accompanying drawing wherein:

Fig. 1 is a perspective view of a fragment of a Venetian blind including a portion of one of the ladders, a portion of the plurality of slats and one of the lifting cords such as would be found in ordinary blind construction.

Fig. 2 is a vertical sectional view taken through a portion of the ladder shown in Fig. l and illustrating the inter-connection of the cross bars with the vertical tapes forming the ladder.

Fig. 3 is a detail fragmentary sectional view of a portion of the cross bar member and illustrating the manner in which the stiffening material may be included within a coating of plastic or other suitable covering material and illustrating the shape of the ends of the cross bar which adapts them to be attached to the vertical tapes.

Fig. 4 is a fragmentary perspective view of a part of a length of a strip of material which has been preformed and from which sections may be cut to form cross bars for ladders, this view illustrating the manner in which the stiffening material is disposed within the outer coating material, and

Fig. 5 is a fragmentary perspective view of a portion of a slat having a notch instead of the cord slot to make the slat removable.

Referring to the drawings we have illustrated in Fig. 1 a portion of a Venetian blind, which as will be understood by those skilled in this art includes suitable headrail, tilting structure and other structure ordinarily found in a Venetian blind, but not deemed necessary to be illustrated, herein, Fig. 1 illustrating particularly a portion of one of the ladders which will be employed with such assembly as comprising a pair of vertical tape members I and 2, which are disposed parallel to each other and are spaced apart a sufficient distance to permit the insertion therebetween of a plurality of Venetian blind slats 3. The slats are supported in parallel relation to each other and in spaced relation to each other by resting upon cross bars 4, forming a part of the ladder,

the cross bars 4 extending between the vertical tapes I and 2 and having their ends secured to the vertical tapes in such fashion as will permit the ready flexing of the junction between the cross bar and the vertical tape as the vertical tapes are moved relative to each other in the tilting of the slats between open" and closed positions.

The usual construction of Venetian blind slats includes elongated slots 5 through which extends a cord 6 by which the blind may be raised and lowered, the slots terminating short of the edges of the slats. If the blind is one utilizing removable slats the cord 6 extends through notches in the slats which notches correspond substantially to the slots 5 except for the fact that one end of each of the slots extends to the extreme edge of the slats and thus permits the slats to be disengaged from the cord and removed from the ladders without requiring complete disassembly of the entire blind structure. However, it may be desirable to form the notches with a depth which extends only to approximately the center line of the slats.

In the event the ladder is to be made of plastic material as described in the Hunter patent hereinbefore referred to, we provide a stiffening member for the cross bars to render them relatively stiff as compared with the great flexibility of the vertical tapes I and 2 as by means of providing said cross bars with a reinforcing member which lends considerable rigidity thereto. Thus, the cross bars being rendered relatively rigid do not tend to crumple or fold and thus avoids the danger of the cross bars becoming entangled in the slots 5 (or the notches 5, in the event the removable slat structure is employed).

The reinforcing member is preferably an insert which is different from the material from which the cross bars and the vertical tapes I and 2 are constructed, and in the form illustrated herein this reinforcing member takes the form of a relatively thin strip of metal, such as a thin strip of aluminum which is preferably covered or coated with the same plastic material of which the vertical tapes I and 2 are constructed. This type of construction lends itself to ready manufacture as by providing a relatively long length of the reinforcing metal in the form of an elongated strip which is so arranged with the machinery which extrudes or forms the plastic for the cross bars that the plastic material is extruded or otherwise so applied to the upper and lower surfaces of the reinforcing strips as to completely cover the reinforcing strips. Thus the reinforcing strip is concealed by the plastic material and is not visible and does not mar the appearance of the finished reinforced cross bar.

The cross bars are attached at their ends in any suitable manner to the vertical tapes I and 2, so that there is a flexible, articulated joint or junction between the ends of the cross bars and the vertical tapes I and 2, permitting the ready lifting and lowering of tapes I and 2, relative to each other as the tapes are manipulated in the tilting operations of moving the slats between their fully open and their fully closed positions in the normal manipulation of the blind.

We prefer that the reinforcing material shall extend along such part of the length of the cross bar 4 as will lend rigidity to that portion which is disposed between the vertical tapes I and 2. In order that the reinforcing metal shall not interfere in any sense with the flexibility of the junction or the joint between the cross bars and the vertical strips, we prefer to allow a relatively short length of the flexible element of the cross bar or the cross bar to be free of the reinforcement adjacent the extreme ends of the cross bars, that is, the extreme edges of the cross bar strip.

As illustrated particularly in Figures 3 and 4, it will be noted that one way in which the reinforced or stifiened cross bars may be readily constructed is that of forming a relatively long strip of cross bar material, such strip of cross bar material including the reinforcing metal coated on both of its sides with the plastic or other flexible material and having along the edges of said strips, a sufficient area of the strip formed solely of plastic or flexible material so as to provide the flexible joint hereinbefore referred to. It will also be noted from an inspection of Figs. 2, 3, and 4 that the extreme edge of the strip is preferably formed with a flare in both directions as indicated at 8 and 9, thereby providing a relatively flat edge portion ID of considerable area disposed at right angles to the lateral axis of the strip of cross bar material. The flat surface is therefore provided to make a secure joint with the vertical strip material l and 2 by the application of cement, a liquid plastic or other means well known in the art by which two members may be joined together, the relatively wide area of the fiat portion It insuring a strong joint between the cross bars and the vertical tapes so as to withstand the Working of the joints in the normal operation of the blind in use.

In addition it will be observed that the flarin at 8 and 9 of the edge material, also provides a fillet which will aid in lending great strength to the joint between the cross bars and the vertical tapes and particularly avoids the tendency of the cross bars to tear away from the vertical tapes, especially when the flexible material used is one of the plastics such as one of the vinyl or similar plastics.

The strip of cross bar material manufactured independently of the vertical tapes I and 2 may be cut into segments of any suitable width to form cross bars of the desired width dimensions and may be punched with openings of any suitable size through which the lifting and lowering cord 6 may extend. These cut strips for the cross bars may then be applied in any suitable manner to the vertical tapes I and 2 as described to form the completed ladder.

It will be observed from the foregoing that the cross bars 4, being relatively rigid will not sag or fold and thus become entangled with the slats, and will not in any sense interfere with the desired flexibility of the vertical tapes in the normal bunching or the vertical tapes as the blind is lifted or lowered.

Thus, at all times, the slats tend to lie parallel with each other and regardless of the number of times or the speed with which the blind is manipulated between its open and closed positions, the slats will remain in parallel relations with each other, producing the desired results.

While we have shown and described the preferred embodiment of our invention we do not desire to be limited to any of the details illustrated and described except as defined in the appended claims.

We claim:

1. Material to be used for forming a plurality of cross bars of Venetian blind ladders comprising an elongated strip of flexible plastic material and a strip of substantially more rigid reinforcing material embedded in the flexible plastic material, said strip of reinforcing material having a width less than the Width of the strip of flexible plastic material and being spaced from each side edge of the flexible plastic material to leave un-reinforced portions at the edges of said strip to form flexible joints with vertical tapes of a Venetian blind, the opposite surfaces of said strip at each edge flaring outwardly to provide an extended attachment surface at each side of the strip.

2. Material to be used for forming a plurality of cross bars of Venetian blind ladders as defined in claim 1 in which the extended attachment surface at the side edges are flat.

THOMAS A. MARTIN.

JOSEPH L. HUNTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,810,438 Rado June 16, 1931 1,937,342 Higbie Nov. 28, 1933 2,381,060 Kahn Aug. 7, 1945 2,405,579 Hunter Aug. 13, 1946 2,517,788 Herron Aug. 8, 1950 2,535,926 Hunter et al Dec. 26, 1950 2,536,472 Sherwood Jan. 2, 1951 

